ART: Decrease dex2oat watchdog timeout

Keep the dex2oat watchdog timeout lower than the package manager
timeout, so that dex2oat kills itself before the system server
watchdog kills the system because of the long installation.

Bug: 23629410

(cherry picked from commit 540138ae)

Change-Id: I5faa23a1715736a1c2ba3f302a6ee41130d3fbae